Fuel Pump Volume

[John_Walker (69 FHC. . . $ via PayPal)]

What is an acceptable volume of fuel pumped per minute in unrestricted flow for a Series II SU fuel pump? I just measured mine and it pumps just at 6 cups in one minute. I didn’t check the pressure.

I’ve seen a number somewhere but can’t find it in either the Haynes or Bentley manuals.

[soothsayer1 (LLoyd (just a rithmetician))]

“Arithmetically speaking” at that rate you are using a gallon in less than six minutes, something short of a tank an hour.
I think that rate is adequate for normal driving.
LLoyd

[John_Walker (69 FHC. . . $ via PayPal)]

@soothsayer1

Arithmetically speaking" at that rate you are using a gallon in less than six minutes, something short of a tank an hour.
I think that rate is adequate for normal driving.

Thanks Lloyd, that’s my thinking as well.

[Heuer (David Jones)]

From the SU service manual:

“The pump is capable of supplying approximately 75 (Imperial) pints of fuel per hour at a delivery point about 3 ft. above the level of the tank with 1/4” bore pipes. It is thus capable of supplying fuel at this rate when ascending the most severe gradient liable to be encountered."

SU carbs require a fuel pressure of approximately 2.5 psi. Both the Lucas and SU pumps produce a pressure in excess of 4 psi.

David

[John_Walker (69 FHC. . . $ via PayPal)]

@Heuer

The pump is capable of supplying approximately 75 (Imperial) pints of fuel per hour at a delivery point about 3 ft. above the level of the tank with 1/4" bore pipes. It is thus capable of supplying fuel at this rate when ascending the most severe gradient liable to be encountered."

Thanks David.

So, 1442 us oz. per hour. Divide by 60 and I get 24 us oz., 3 cups, per minute . I had my receptacle at fuel filter level and was getting about 6 cups per minute, so I think I’m probably OK. I’ll probably redo the test with the end of the discharge hose elevated and see what I get when I put my pressure test rig together.